An unmarked door on the 102nd-floor observation deck conceals one of the most impractical secrets of this towering landmark. Although visitors can't access it, a set of steps leads to a narrow terrace that was once intended to be a docking station. Airships were supposed to moor at the tip of the mast, and passengers would be able to alight there. (But don't be fooled—though this image illustrates what such an event might have looked like, it's a fake.) A late addition to the design, the mast may have simply been an excuse to make the building the world's tallest. Given the strong winds at 1,250 feet—not to mention the logistics of a landing crew—it's now known that no dirigible could feasibly dock there. A three-minute jerry-rigged connection in September 1931 in 40-mile-an-hour winds was the closest the plan ever came to fruition. 350 Fifth Ave between 33rd and 34th Sts (esbnyc.com)